ActivAcción: Implementation Feasibility, Acceptability, and Safety of a Task-Specific Functional Activation Protocol for Forest Firefighters Occupationally Exposed to Wildfire—A Pilot Study in Chile

Abstract

Forest firefighters face concurrent thermal stress, biomechanical loading, high metabolic demand, smoke, and time-constrained manual work, conditions that increase musculoskeletal disorder (MSD) risk. In Chile, occupational health regulation requires biomechanical risk management, but no task-specific activation protocol has been evaluated within wildfire suppression operations. This pilot study assessed the feasibility, acceptability, and safety of ActivAcción, a 5 min dynamic activation protocol integrated into Corporación Nacional Forestal (CONAF) wildfire brigade routines. A single-group mixed-methods feasibility study was conducted over 8 weeks at the Placilla CONAF base, Valparaíso Region, Chile. Ten firefighters and supervisors participated. The intervention included two educational sessions and an eight-exercise routine adapted from the WFX-FIT manual and delivered within existing safety briefings. Outcomes were adverse events, musculoskeletal complaints, perceived feasibility and acceptability, implementation fidelity, and qualitative themes. No adverse events or new musculoskeletal complaints were recorded. Feasibility and acceptability ratings were high among brigadistas (mean, 6.71/7.0, SD = 0.69) and maximal among supervisors (7.0/7.0). Protocol fidelity reached 75% (12/16 sessions). Qualitative findings identified task-specificity, ease of integration, and leadership endorsement as implementation facilitators. ActivAcción is feasible, acceptable, and safe under the studied low-exposure conditions; controlled high-season evaluation is required before inference on MSD prevention effectiveness.

1. Introduction

Wildfire suppression is recognized as one of the most physiologically extreme occupational exposures in the world. Forest firefighters operating in active fire environments are simultaneously subjected to thermal stress from radiant heat and environmental temperature, sustained biomechanical loading from manual tool use and terrain locomotion under load, extreme metabolic demand (energy expenditure exceeding 25 MJ/day), smoke inhalation, and acute psychological stress [1,2,3,4]. These compounded wildfire exposure conditions are not merely occupational descriptors; they constitute a cumulative hazard environment in which physiological systems operate near their functional limits [5,6].

Within this exposure context, musculoskeletal disorders (MSDs) represent a leading category of occupational injury. Chronic low-back pain, knee pathology, shoulder discomfort, and overuse injuries are consistently documented in wildland firefighter cohorts and in the broader work-related MSD literature, and are directly linked to the biomechanical demands of wildfire suppression tasks—including repetitive tool-use cycles, manual load handling, postural constraints during firebreak construction, and prolonged hillside locomotion [7,8,9,10]. Critically, MSD risk in this population is not simply a function of occupational category; it is modulated by the intensity and duration of wildfire exposure itself, which varies substantially across and within fire seasons [4,5].

In Chile, the Corporación Nacional Forestal (CONAF) operates the national wildfire suppression system under a normative framework (Ley 16.744; DS 44/2024; TMERT Protocol, MINSAL 2021) that explicitly mandates integrated biomechanical risk management programs. Occupational health data from CONAF’s Safety and Occupational Health Unit (USSO-CONAF) for 2020–2025 document that musculoskeletal structures were involved in more than 50% of 497 recorded work injuries and incidents—including sprains, low-back episodes, contusions, and overexertion events. These data confirm that MSD risk factors are active and consequential within the Chilean wildfire suppression workforce.

Despite this burden, a critical evidence gap persists at the intersection of wildfire exposure and MSD risk mitigation. Chilean occupational health legislation—specifically Ley 16.744, its implementing regulation DS 44/2024, and the TMERT Protocol (MINSAL, 2021)—explicitly mandates that employers implement integrated biomechanical risk management programs developed in participation with workers. This regulatory obligation creates a concrete institutional requirement for preventive action. However, the legislation defines the obligation without specifying the operational mechanisms through which compliance must be achieved: it mandates that measures be taken and that they be developed collaboratively, but does not prescribe what those measures should be. For wildfire suppression brigades, this regulatory gap—between the mandate to act and the absence of validated tools to act with—remains unaddressed, despite earlier ergonomic work in Chilean forest-fire brigades [11]. No task-specific, context-adapted functional activation protocol has been systematically developed and evaluated for use within actual wildfire suppression operational structures in Chile or the broader Latin American context [12,13]. Existing workplace and sport warm-up research, while supportive of the intervention category in non-wildfire settings [14,15,16], has not been transferred to the distinct operational and environmental characteristics of wildfire suppression work. The intensity of biomechanical loading during active fire events, the constraint of operational time, and the cultural and institutional context of forest firefighting brigades require purpose-adapted protocols and dedicated implementation evidence before efficacy evaluation is meaningful [4,17].

Implementation science frameworks establish that acceptability, feasibility, and safety must be demonstrated before advancing to efficacy trials [18,19,20]. This study responds to that requirement by presenting ActivAcción, a brief functional activation protocol culturally adapted for CONAF forest firefighters within a wildfire exposure context. The sole objectives of this pilot are to evaluate: (1) operational feasibility of protocol delivery within existing brigade structures; (2) user and supervisor acceptability; and (3) absence of adverse events during the implementation period. This study was not designed to evaluate MSD prevention outcomes.

2. Materials and Methods

2.1. Study Design and Setting

This was a pre-experimental, single-group, mixed-methods feasibility pilot conducted over 8 weeks (10 September–10 November 2025) at the Placilla fire brigade base (CONAF, Valparaíso Region, Chile). The study coincided with the low-incidence fire season, which reduced real-world fire suppression exposure but allowed educational delivery and protocol implementation without operational disruption—a design characteristic appropriate for this stage of intervention development [19,20]. The study was not designed nor powered to detect changes in MSD incidence.

2.2. Sample Size Justification

For feasibility pilots, sample size is governed by the objectives of the study—feasibility, acceptability, and safety observation—rather than by statistical power for outcome detection [19,20]. A convenience sample of $N=10$ was considered appropriate to assess protocol delivery, identify implementation barriers and facilitators, and generate acceptability data with sufficient variability to inform future RCT design. This is consistent with published guidance recommending 10–30 participants for early-phase feasibility pilots in occupationally defined cohorts.

2.3. Participants

A convenience sample of 10 firefighters participated: 7 brigadistas (entry-level), 2 squad leaders (jefes de cuadrilla), and 1 brigade chief (jefe de brigada). Ages ranged from 26 to 51 years (mean, 37.4 ± 9.57); 80% were male ($n=8$). Mean occupational experience was 7.2 fire seasons (SD = 4.75; median = 7.5). Detailed characteristics are presented in

Table 1. Participant characteristics ($N=10$).

Participant	Sex	Age (Years)	Role	Experience (Seasons)
S1	Female	27	Brigadista	3
S2	Female	32	Brigadista	3
S3	Male	51	Brigadista	11
S4	Male	26	Brigadista	2
S5	Male	50	Brigadista	2
S6	Male	31	Squad Leader	9
S7	Male	40	Brigade Chief	16
S8	Male	42	Squad Leader	11
S9	Male	29	Brigadista	9
S10	Male	46	Brigadista	6
Summary		37.4 ± 9.57		7.2 ± 4.75

.

Inclusion criteria: (1) Active employment at the Placilla base during the study period; (2) absence of musculoskeletal complaints in the 4 weeks prior to enrollment, confirmed by self-report. Exclusion criteria: Acute injuries, recent surgery, or medical contraindications to dynamic exercise.

This study did not undergo formal review by an institutional ethics committee. Procedures were implemented in accordance with ethical and regulatory principles for minimal-risk occupational field research: all participants signed written informed consent prior to participation, institutional authorization was obtained from CONAF, and CIFFC authorized use and adaptation of the dynamic warm-up section of the WFX-FIT manual.

2.4. Intervention: ActivAcción

The ActivAcción intervention was implemented in two sequential phases.

The study used no chemicals, reagents, biological samples, commercial devices, or proprietary instruments. The intervention required no equipment. No commercial statistical software was used; quantitative results were calculated descriptively and qualitative coding was performed manually.

2.4.1. Phase 1: Theoretical Capacitation (Weeks 1–2)

Content addressed: (1) Occupational physiology of wildfire suppression—metabolic demand (>25 MJ/day), sustained cardiovascular load (∼40% $\dot{V}$${\mathrm{O}}_2$max), and thermal stress; (2) epidemiology and mechanisms of MSD risk factors in forest firefighting; (3) specific biomechanical risk exposures: repetitive tool use, manual load handling, postural constraint during firebreak construction; (4) rationale for functional activation and dynamic warm-up within wildfire exposure contexts; and (5) Chilean occupational health regulatory framework (Ley 16.744; DS 44/2024; TMERT Protocol). Delivery methods included dialogued lecture, multimedia presentation, case analysis from local CONAF injury records, and group discussion.

2.4.2. Phase 2: Practical Capacitation and Protocol Implementation (Weeks 2–8)

Participants learned and practiced the standardized ActivAcción routine: a 5 min dynamic activation sequence of 8 exercises adapted from the WFX-FIT manual (CIFFC, 2012) [21] and culturally adapted for the Chilean wildfire suppression context. The complete protocol, including exercise descriptions and their biomechanical correspondence to specific wildfire suppression tasks, is presented in

Table 2. ActivAcción protocol: Exercise sequence, description, dose, and wildfire task-specific rationale (adapted from WFX-FIT, CIFFC, 2012 [21]).

No.	Exercise	Description	Dose	Wildfire Task Correspondence
1	Rebounding movements	Bilateral low-amplitude vertical rebounds; arms swing freely	30 s	Neuromuscular priming; cardiovascular activation
2	Vegetation-clearing simulation	Bilateral horizontal sweeping with progressive trunk rotation; mimics tool arc	30 s	Lateral tool-swing pattern (raking, brushing); shoulder girdle mobility
3	Sumo squats	Wide-stance squat; upright trunk; progressive depth; heels grounded	8 reps	Lower-limb loading for load-carrying and hillside locomotion
4	Lunges with trunk rotation	Alternating forward lunges; contralateral arm rotation at lowest point	8 reps/side	Hip-flexor elongation; rotational trunk control; terrain navigation
5	High-knee march with rotation	High-knee march with contralateral trunk rotation; controlled cadence	20 m	Hip flexor activation; slope-walking coordination pattern
6	Goose walk	Forward ambulation in sustained deep squat; hands on knees	10 m	Quadriceps and glute endurance; lumbar stability under load
7	Quadriceps elongation	Unilateral standing knee flexion; single-leg balance; upright trunk	20 s/side	Anterior chain flexibility; ankle proprioception
8	Ankle-to-toe touches	Unilateral posterior chain elongation; controlled forward lean	20 s/side	Hamstring and calf flexibility; ankle-knee stability on uneven terrain

Total duration: ≈5 min. No equipment is required. It was delivered within the existing charla de seguridad structure.

. Teaching methodology included guided demonstration, supervised cohort practice, and immediate technical feedback.

The protocol was integrated into existing pre-shift safety briefing structures (charlas de seguridad), leveraging an established organizational channel to minimize operational disruption—consistent with implementation science recommendations [12,22].

2.5. Outcome Measures

2.5.1. Primary Outcome: Safety (Absence of Adverse Events and Incident Complaints)

A graphical musculoskeletal symptom assessment instrument (adapted from Nordic questionnaires and Chilean TMERT surveillance protocols [23]) was administered at baseline and the endpoint. Participants indicated the presence or absence of pain or discomfort in seven anatomical zones: neck, shoulders/arms, forearms/hands, thoraco-lumbar spine, hips/thighs, knees, and legs/feet. This instrument was selected as a safety monitoring tool, not as an efficacy outcome measure. The graphical format was selected to accommodate the heterogeneous literacy levels of this occupational population (minimum formal education for brigadista employment: 8th grade).

2.5.2. Measurement of Feasibility and Acceptability

A self-administered Likert-scale questionnaire (1–7) assessed three dimensions: (1) ease of protocol application; (2) perceived utility of the protocol for targeting MSD risk factors; and (3) feasibility of systematic long-term implementation within brigade operations. Open-ended prompts captured barriers, facilitators, and refinement suggestions. Separate instrument versions were administered to brigadistas and supervisory staff.

2.5.3. Process Outcomes

Session attendance records, facilitator field notes, and adherence observations documented implementation fidelity throughout the 8-week period.

2.6. Data Analysis

2.6.1. Quantitative Analysis

Symptom data were coded dichotomously (0 = absent, 1 = present) per anatomical zone and reported descriptively at baseline and the endpoint. Given the sample size ($N=10$) and the exploratory nature of the pilot, no inferential statistics were applied [19]. Likert-scale data are summarized with descriptive statistics (mean, median, SD, and frequency distributions) per dimension. All analyses were conducted at the descriptive level only; this study was not designed to detect or attribute changes in symptom status.

2.6.2. Qualitative Analysis

Open-ended responses and field notes underwent thematic analysis following Braun and Clarke [24]. Three analytical stages were applied: (1) immersive reading and identification of meaning units; (2) open coding and categorical grouping; and (3) synthesis and cross-tabulation with quantitative data to identify convergent and discrepant findings [25].

2.7. Ethical Approval

The study did not undergo formal review by an institutional ethics committee. The procedures were implemented in accordance with ethical and regulatory principles applicable to minimal-risk occupational field research. All participants signed written informed consent prior to participation. Institutional authorization from the CONAF Valparaíso Region was secured prior to data collection, and permission to use and adapt the WFX-FIT dynamic warm-up section was granted by the CIFFC Operations Director (D. Bokovay, personal communication). No personal health identifiers were reported, and all results are presented in aggregate form.

3. Results

3.1. Participant Characteristics and Operational Context

The sample comprised 10 firefighters (mean age, 37.4 ± 9.57 years; 80% male; mean, 7.2 seasons’ experience; Table 1). All participants were asymptomatic at baseline across all seven anatomical zones. No pre-existing injuries or contraindications were documented. The eight-week study period coincided with the low fire-incidence season; the Placilla base responded to occasional fire events but sustained high-intensity suppression demands were absent. This operational context is relevant to interpreting all findings: participants were not exposed to peak wildfire exposure conditions during the study period.

3.2. Primary Outcome: Safety

All 10 participants reported continued absence of musculoskeletal complaints across all seven anatomical zones at post-intervention assessment. No new symptoms, adverse events, injuries, or complaints attributable to protocol participation were documented at any point during the eight-week period. These observations are consistent with the safety of the protocol under the specific implementation conditions studied; they do not constitute evidence of protective efficacy and are not interpretable as such given the baseline-asymptomatic status of participants and the low-exposure operational period.

3.3. Secondary Outcomes: Feasibility and Acceptability

3.3.1. Supervisory Staff ($n=3$)

All three supervisors (brigade chief and two squad leaders) assigned maximum ratings (7.0/7.0; SD = 0.00) to all evaluation dimensions: perceived utility of the protocol for targeting MSD risk factors, importance of systematic implementation, and importance of long-term integration. No variability was observed.

3.3.2. Brigadistas ($n=7$)

Firefighters reported high acceptability across all dimensions (aggregate mean, 6.71/7.0; SD = 0.69). Item-level distributions were: ease of application (6 rated 7.0; 1 rated 5.0); perceived utility for targeting MSD risk factors (6 rated 7.0; 1 rated 5.0); and feasibility of systematic implementation (6 rated 7.0; 1 rated 5.0). Summary data are presented in

Table 3. Perceived feasibility and acceptability ratings by role group (Likert scale 1–7; higher = greater agreement).

Dimension	Brigadistas ($\mathit{n}=7$)	Supervisors ($\mathit{n}=3$)
	Mean (SD)	Mean (SD)
Ease of application	6.71 (0.76)	7.00 (0.00)
Perceived utility (targeting MSD risks)	6.71 (0.76)	7.00 (0.00)
Feasibility of systematic implementation	6.71 (0.76)	7.00 (0.00)
Aggregate	6.71 (0.69)	7.00 (0.00)

.

3.3.3. Qualitative Themes

Thematic analysis identified three convergent themes across brigadista and supervisory open-ended responses (

Table 4. Qualitative themes from thematic analysis of open-ended responses and field notes.

Theme	Illustrative Quotes	Convergence with Quantitative Data
Perceived task-specificity	“You notice it at the start of fieldwork”; “Activates the muscles needed for the ergonomic demands of the work”	Consistent with high perceived utility ratings (mean, 6.71–7.00)
Integration ease and brevity	“Very positive, cost-effective measure”; “It does what it needs to without taking time”	Consistent with high implementation feasibility ratings
Leadership endorsement	“Prepares muscles for the activity”; “Works as an effective activation before fighting fires” (supervisors)	Supported by unanimous maximum supervisor ratings

).

One minority view (one of seven brigadistas, consistently rating 5/7) identified potential difficulty implementing the protocol during rapid-deployment fire events—a barrier triangulated with the four disrupted sessions documented in field notes.

3.4. Protocol Adherence and Implementation Fidelity

The ActivAcción protocol was delivered on 12 of 16 planned occasions (75% fidelity). Four sessions were disrupted by elevated fire-suppression demands or personnel scheduling constraints associated with fire incidents. Attendance at theoretical sessions averaged 90% (9/10 participants per session). No adverse events, injuries, or protocol-related complaints were documented.

4. Discussion

4.1. Summary of Supported Findings

This pilot study demonstrates that ActivAcción—a 5 min dynamic activation protocol adapted from the WFX-FIT manual for Chilean wildfire suppression operations—can be operationally delivered, is accepted by both end-users and supervisory personnel, and produced no adverse events under the studied implementation conditions. These findings address the three feasibility objectives of this study [18,19]: the protocol was deliverable within operational constraints; the target population accepted it; and no safety concerns emerged.

4.2. Small-Sample Inference and Generalizability

The relationship between the small sample and the generalizable contribution of this study is limited to implementation inference, not population inference. With $N=10$ from one CONAF base, the data cannot estimate MSD incidence, injury-rate reduction, or between-brigade variability with statistical precision. The generalizable element is therefore analytical and procedural: a 5 min, equipment-free, task-specific activation protocol can be embedded within an existing wildfire brigade safety briefing, delivered with 75% fidelity during routine operations, and accepted by both firefighters and supervisory personnel under the conditions studied. These findings justify progression to a larger controlled design but do not support claims of clinical or epidemiological effectiveness. A subsequent trial should treat brigades as the unit of allocation, include multiple bases and regions, and be conducted during peak wildfire exposure to test whether implementation feasibility persists under higher operational load.

4.3. Alignment with Implementation Science Principles

The design and findings are consistent with implementation science principles, which require acceptability, feasibility, and safety to be established prior to efficacy investigation [18,19]. The high acceptability ratings from both brigadistas and supervisors indicate that two critical preconditions for sustained program uptake are present: end-user acceptance and leadership endorsement [26,27]. The integration of ActivAcción within pre-existing charlas de seguridad represents a deliberate “fit” strategy—leveraging established organizational infrastructure rather than creating new operational demands—which implementation science identifies as a facilitator of sustained adoption [12].

4.4. Positioning Against Workplace Warm-Up Literature

The implementation characteristics of ActivAcción—brevity, task-specificity, and organizational integration—are consistent with implementation features identified in the warm-up literature as associated with feasibility and user uptake [14,15]. It must be stated explicitly, however, that ActivAcción has not demonstrated outcomes consistent with those reported in efficacy studies. The present findings establish only that the protocol shares implementation-relevant characteristics with programs that have been evaluated for efficacy in other occupational populations. Whether equivalent outcomes would be observed in the wildfire suppression context requires evaluation under higher-exposure conditions with an appropriate controlled design.

4.5. Task-Specificity and Acceptability

The high acceptability ratings from brigadistas (86% maximum) and unanimous maximum ratings from supervisors may reflect perceived alignment between the protocol’s exercise selection and specific wildfire suppression movement demands: lower-limb dynamic loading (sumo squats, lunges), rotational trunk control (lunges with rotation, vegetation-clearing simulation), and lower-extremity stability on uneven terrain (ankle-to-toe touches, goose walk). Perceived task-relevance is a documented facilitator of user engagement and protocol adherence in occupational exercise programs [28,29], and its presence here supports the feasibility of sustained implementation. It does not, however, provide evidence of efficacy.

4.6. Regulatory and Normative Context

ActivAcción addresses an implementation gap between the biomechanical risk management requirements of Chilean occupational health legislation (Ley 16.744; DS 44/2024; TMERT Protocol) and the absence of operationally validated tools for compliance within wildfire suppression brigades. CONAF’s injury data (musculoskeletal events comprising >50% of recorded incidents) confirm the epidemiological relevance of this gap. The protocol constitutes a concrete administrative control that translates regulatory intent into operational practice—though its effectiveness as a control measure requires further evaluation before such claims can be made.

4.7. Interpretation Boundaries

The following constraints limit the inferential scope of these findings and must be stated explicitly:

• Asymptomatic baseline. All participants were free of musculoskeletal complaints at enrollment. Under this condition, no meaningful change in symptom status can be observed or attributed. The study was therefore structurally incapable of addressing MSD symptom reduction.
• Low wildfire exposure period. The intervention was conducted during the low-fire-incidence season (September–November). Participants were not exposed to the peak biomechanical, thermal, and physiological demands characteristic of the active fire season (December–March). The risk environment during the study period was materially lower than the target exposure context. No inference about protocol behavior under high-exposure conditions is warranted.
• Absence of a control condition. The single-group design provides no basis for attributing the observed symptom stability to the intervention. The observed absence of complaints is fully consistent with the null hypothesis that symptom status would have remained stable without any intervention during a low-exposure period.
• Small convenience sample. $N=10$ from a single base limits generalizability to other brigades, regions, or operational contexts.
• Short follow-up. Eight weeks is insufficient to assess behavioral sustainability or any medium-term effects on musculoskeletal health.

These constraints are inherent to and appropriate for this phase of intervention development. They do not constitute methodological failures; they define the boundary of what this study was designed to address.

4.8. Protocol Adherence and Operational Barriers

The 75% fidelity rate (12/16 sessions) reflects a genuine operational constraint: rapid-deployment fire events create time pressures that are incompatible with non-emergency activities. This barrier—identified both in field notes and in one minority qualitative response—will require explicit design consideration in future implementation. Options include integration at the end of the charla with a conditional skip protocol during rapid-response deployments, or designation of specific low-intensity operational periods as structured activation windows.

4.9. Path Toward an Efficacy Trial

The present feasibility data provide the prerequisite evidence base for a rigorous efficacy study. A recommended design would include: timing during the active fire season (December–March); a cluster-randomized controlled trial with brigades as randomization units; ActivAcción versus standard safety briefing (control); primary outcomes of incident MSD rates, acute musculoskeletal complaints, and injury-related duty restrictions; secondary outcomes of perceived physical readiness and Pack Test performance; full-season follow-up (4–6 months) with monthly assessments; and a power calculation targeting a 30–50% reduction in MSD incidence based on occupational health research in comparable high-demand manual worker cohorts [12,14].

4.10. Emergent Findings: Team Cohesion and Workforce Engagement

Beyond the pre-specified implementation outcomes, two findings emerged from field observation and qualitative data that were not originally anticipated. First, the collective delivery format of ActivAcción—performed as a group activity immediately before the daily safety briefing—was perceived by participants and supervisors as a shared physical routine that supported brigade-level cohesion. This finding is observational and qualitative; it should be interpreted as an implementation facilitator, not as a measured psychosocial outcome. Second, the near-maximum acceptability scores (95.9% among brigadistas; 100% among supervisors) and the 90% attendance at theoretical sessions indicate high workforce engagement under the studied conditions. This convergence of end-user acceptance and active supervisory participation is consistent with implementation science criteria for adoption readiness [18,26]. These emergent findings have implications for scalability because they identify candidate mechanisms for sustained uptake: brief duration, collective delivery, and supervisor-led integration within existing operational routines.

4.11. Implications for Wildfire Occupational Health Practice

ActivAcción represents a low-cost, equipment-free, operationally integrated tool that targets MSD risk factors within the wildfire exposure context. Its scalability across CONAF bases and regions is supported by the structural characteristics demonstrated here: 5 min duration, no equipment requirement, and compatibility with existing operational routines. Training supervisors as designated “activation leads” creates a sustainable delivery model within existing organizational hierarchies, consistent with participatory implementation approaches [12,13]. These characteristics position ActivAcción as a candidate occupational health intervention in the wildfire suppression sector, pending efficacy evaluation.

5. Conclusions

ActivAcción was feasible to deliver, acceptable to firefighters and supervisors, and safe under the low-exposure implementation conditions studied. The protocol was completed in 12 of 16 planned opportunities (75% fidelity), generated no adverse events or new musculoskeletal complaints, and obtained high acceptability ratings from brigadistas (mean, 6.71/7.0) and maximum ratings from supervisors (7.0/7.0). Qualitative data identified perceived task-specificity, ease of integration into existing safety briefings, and leadership endorsement as implementation facilitators.

The evidence supports progression to a controlled efficacy trial, not immediate claims of MSD prevention effectiveness. The next evaluation should be conducted during the peak wildfire season, include multiple CONAF bases, use brigade-level randomization, and measure incident MSD rates, acute musculoskeletal complaints, duty restrictions, adherence, and implementation fidelity over a full operational period. Under those conditions, ActivAcción can be tested as a candidate occupational health intervention for wildfire suppression work rather than only as a feasible implementation protocol.